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Influence of cycling on microstructure and hydriding/dehydriding properties of nanocrystalline magnesium hydride with nanosized niobium fluoride
|Iwona E. Malka , Jerzy Bystrzycki|
Military University of Technology, Faculty of Advanced Technology and Chemistry, Kaliskiego 2, Warszawa 00-908, Poland
Magnesium hydride (MgH2) is a promising material for hydrogen storage applications because of its high gravimetric (7.6 wt.%) and volumetric (110 kg m-3) densities and low cost. However, there are some drawbacks limited practical application of this hydride. First of all, it is too stable thermodynamically (H=-75 kJ/mol). It results in high desorption temperature (>400ºC). Moreover, the MgH2 exhibits relatively poor absorption/desorption kinetics below 350ºC. Recently, it has been shown that the sorption kinetics of MgH2 can be dramatically improved by ball milling of MgH2 with some transition metals and their oxides or halides. Among them, NbF5 additive seems most significantly enhance the sorption kinetics of MgH2. However, it is still not clear how the NbF5 promotes the dehydrogenation and hydrogenation reactions. Additionally, there is a lack of information about microstructure and sorption properties of MgH2 with nanosized NbF5 after cycling loading.
Presentation: Poster at E-MRS Fall Meeting 2008, Symposium D, by Iwona E. Malka
See On-line Journal of E-MRS Fall Meeting 2008
Submitted: 2008-05-12 09:39 Revised: 2009-06-07 00:48